1. Field of the Invention
The present invention relates to a magnetic recording medium for use as a video tape, audio tape, memory tape, magnetic recording card, etc.
2. Description of the Art
A magnetic recording medium basically comprises a magnetizable layer provided on one side of a support. When the adherence of the magnetizable layer to the support is poor, the layer has been provided on an undercoated support; and when the magnetic recording layer comprises multiple, laminated layers, a layer having dispersed therein a powdered material having a lubricating property, such as graphite, tungsten sulfide, or molybdenum sulfide, etc., has been provided on the back side of the support opposite the side provided with the magnetizable layer for improving the running of the magnetic recording medium. Further, an electrically conductive layer having dispersed therein fine powder of an electrically conductive substance such as carbon black, graphite, etc., has been provided on the back side of various magnetic recording materials for making the magnetic recording medium antistatic.
Heretofore, a transparent plastic film has been used as the support of magnetic recording media. However, the back surface of such media shows the color of the magnetizable layer (dark brown) through the support and the back surface of a magnetic recording media provided with a gliding layer, electrically conductive layer, etc., is black in color.
Further, a magnetic recording medium, after recording, must be identified by marking on the medium or on its package (case, reel or outer packaging box) because the recording on the magnetic recording medium is not visible.
Various colored tapes have been attached to a magnetic recording medium to identify the recording. However, in the case of putting numerous and various recordings on the same magnetic recording medium, it would be convenient to make it possible to put a mark on the magnetic recording medium directly. This is fact would be preferred in order to produce the same number of markings as the number of the recordings.
Considering the fact that a black or dark colored material, such as a pencil or ink, is generally used for marking, and that black writing on a white background is more easily discerned than white writing on a black background, the back surface of a magnetic recording medium is preferably white to make it possible to use numerous marking materials. For this purpose, a layer having dispersed therein a white or light colored pigment has been provided on the back surface of the support of a magnetic recording medium. However, such a construction for a magnetic recording medium has the defect of being high in electric charge, and since the electrification of a magnetic recording medium tends to cause electrostatic adsorption of dust thereon, the result is a situation extremely unfavorable for recording onto the magnetic recording medium or the regeneration thereof.